聚羟基铝柱撑硅藻土的制备及其对水溶液中Cu^(2+)、Zn^(2+)的吸附特性

Preparation of Poly-hydroxy-aluminum Pillared Diatomite and Characteristics of Cu^(2+),Zn^(2+) Adsorption on the Pillar in Aqueous Solutions

鉴于天然硅藻土因理化构造缺陷而导致的吸附性能局限性和传统物化方法对硅藻土改性效果的有限性,为了显著改善硅藻土的吸附性能,采用聚羟基铝对硅藻土实施了柱撑改性.通过扫描电镜(SEM)、红外光谱(FTIR)、X射线衍射(XRD)分析了硅藻土柱撑前后理化特性的变化,并考察了柱撑前后硅藻土表面性能及其对Cu^(2+)、Zn^(2+)吸附特性的差异.结果表明,硅藻土最佳柱撑条件为n(OH-)/n(Al3+)=2.2、KCl浓度1.8 mol·L^(-1)、Al/土比10 mmol·g^(-1)、反应温度60℃、反应时间24 h、老化温度200℃、老化时间0.5 h.柱撑后,聚羟基铝被成功置入硅藻壳体内部,形成了有效柱体,增大了孔道间距,拓展了吸附反应界面,使微孔表面羟基数量增多,表面活性增强.柱撑前后硅藻土对Cu^(2+)、Zn^(2+)的等温吸附特性均符合Langmuir模型,吸附动力学特性均符合二级动力学模型.柱撑后硅藻土对Cu^(2+)、Zn^(2+)的吸附容量分别达到7.491 mg·g^(-1)、11.312mg·g^(-1),较柱撑前分别提高了32.9%、33.3%,硅藻土吸附性能得到了极大的改善.

As an alternative solution to the limitations in adsorption properties of natural diatomite caused by its physicochemical structure defects and modification effects to diatomite using conventional physical / chemical methods,the diatomite was pillared using poly-hydroxy-aluminum to improve its adsorption properties. The change in physicochemical characteristics of the diatomite before and after pillaring were analyzed by Scanning Electron Microscope（ SEM）,Fourier Transform Infrared（ FTIR） and X-ray Diffraction（ XRD）. The difference in surface properties of diatomite and its adsorption characteristics of Cu2＋,Zn2＋before and after pillaring were analyzed at the same time. The obtained results showed that the optimal conditions for diatomite pillaring were 2. 2 of the[OH-]/[Al3＋] molar ratio,1. 8 mol·L-1of potassium chloride,10 mmol·g-1 of the Al / diatomite ratio,60℃ of the pillaring temperature,24 h of the pillaring time,200℃ of the aging temperature,and 0. 5 h of the aging time. After pillaring,the poly-hydroxyaluminum was successfully exchanged into the diatom shell,forming available pillars,which increased channel spacing,expanded adsorption reaction interface,increased the number of microporous surface hydroxy groups and enhanced the microporous surface activity. The Cu2＋,Zn2＋adsorption data obtained both before and after pillaring well fitted the Langmuir isotherm model and the pseudo-second-order kinetics model. After pillaring,the adsorption capacity of Cu2＋,Zn2＋onto diatomite reached 7. 491,11. 312mg·g-1,with an increasing percentage of 32. 9%,33. 3% respectively,the diatomite adsorption capacity got great improvement.